Place the chicken breast in a bowl with the buttermilk and marinate for at least 30 minutes in the refrigerator.
In a shallow dish, whisk together the almond flour, arrowroot powder, garlic powder, onion powder, smoked paprika, sea salt, and black pepper.
Remove the chicken from the buttermilk, allowing any excess to drip off, and dredge it thoroughly in the flour mixture until fully coated.
Lightly coat the air fryer basket with avocado oil spray and place the chicken inside.
Air fry at 375°F for 12 to 15 minutes, flipping halfway through and applying another light spray of avocado oil, until the coating is golden and the internal temperature reaches 165°F.
While the chicken cooks, whisk the Dijon mustard, raw honey, and Greek yogurt together in a small bowl until smooth.
Serve the hot, crispy chicken immediately with the honey-mustard sauce on the side for dipping.